As a member of the Mysterious Discovery Club, one day Shibaki Kota summons a witch using a witch summoning manual he found in the library. He asks for girls' panties. However, he had no idea. Having his wish granted meant creating a contract with a witch and giving her his life...

When Rurumo appears again, Kota receives magic tickets from her that allow him to freely use magic. Making a human use up the magic tickets was the demoted witch's training. However, Rurumo doesn't know the owner of the tickets dies once they're used up. When Kota learns this from Rurumo's Chiro, he swears never to use the tickets again.

Through the power of a memory alteration spell, Rurumo begins living with the Shibaki family under the guise of Kota's younger sister. Despite them living together, Kota experiences great distress at his inability to do anything to his "younger sister". Meanwhile, in order to punish herself for having too much fun, Rurumo begins working in the cafeteria at Kota's high school, where she makes mistake after mistake.

Strictly cracking down on students and beating offenders with their fists are the West High student council's student monitors. Student monitor Inoue Sumiko has known Kota since elementary school and cannot stand the sight of "Shibaki the pervert".

One summer Sunday, as Rurumo makes mistake after mistake while trying to clean the house, she is sent to deliver something to Kota, who is working at his grandmother's farm. Rurumo heads to the post office to purchase "stamps" to ride the train, with Kota's friends and acquaintances from school spotting her on the way.

Some lowerclassmen witness Kota picking up gravure magazines off the ground. Through his attempt to conceal his actions, he ends up taking three abandoned kittens home. However, his animal-hating mother discovers them, and he decides to keep them at school until he finds homes for them.

Kota and his friends go to the beach at the suggestion of their senior. There they run into the student monitors, their busty classmate Maya, and policewoman Iida. No matter how much Kota recommends it, Rurumo refuses to change out of her witch outfit and into a swimsuit, and it becomes clear she forgot to buy one.

As Kota heads to school, a cute twin-tailed girl with an umbrella descends upon him. Identifying herself as rank 1 witch Warua Haruriri, she offers to establish a contract with Kota.

When Kota flees to save his life, Haruriri offers him free use of magic. Rurumo's former classmate from magic school approached Kota knowing he was Rurumo's contractor.

The serious student monitor Shimomura Masako loves anime and creates her own cosplay. When Masako brings her cosplay accessory to school, she drops it on the ground. Rurumo witnesses the event. Masako already feels a sense of affinity for Rurumo due to her mistaken belief that her witch's outfit is a cosplay and is moved when Rurumo doesn't mock her hobby, inviting her to a cosplay event.

Surrounded by legends of the Japanese wolf since long ago, the town of Okamimura lies deep within the mountains. Members of the Mysterious Discover Club along with Kota, Rurumo, his classmates Nishino, Sugawara, Sakurai, Maya, and the student monitor trio take a train to Okamimura. Transforming herself into a human, Chiro tags along as Rurumo's younger sister.

Hardly anyone comes to see the MDC at the cultural festival. At this rate, they won't be promoted to an official club. In order to raise the visibility of the MDC, they decide to enter the "High School Band Heaven" at Tanako's suggestion. However, when Shibaki and the other members begin practicing, they realize it's too difficult for their male club members...